How do I create mathematical equation double square braces like these ⟦exp⟧ in latex? I failed to find it on google (I created these using word 2010 equation editor). I would like these to be of adjustable height like regular braces if possible.

@Alan: Agree, with the proviso that it took me three goes at drawing the symbol before it came up with the right answer. Detexify ought to have a "wait until I've finished drawing" option.
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Loop SpaceMay 15 '11 at 20:44

@Andrew I use detexify on my phone, so it waits for me. But generally I find it faster to look things up in the Comprehensive Symbols guide.
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Alan MunnMay 15 '11 at 20:46

@Andrew: If you keep drawing it reaccesses the image. It came up in my first attempt. Ok, I got [ after I finished the first part was finished but it jumped to the correct one when I was finished.
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Martin Scharrer♦May 15 '11 at 20:49

Thanks for all these wonderful suggestion, I will look them up next time :)
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LightningIsMyNameMay 15 '11 at 20:50

It shows \llbracket, but not always depending how I draw it.
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Martin Scharrer♦May 15 '11 at 20:55

1

egreg: I agree that it's not always perfect - see my comment on the main question! But one thing that helps is us "training" it (which I did, once it had found the right symbol).
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Loop SpaceMay 15 '11 at 21:03